1. Field of the Invention
The present invention relates to an information processing apparatus, and more particularly, to reduction in startup time of the information processing apparatus.
2. Description of the Background Art
Conventionally, there has been proposed a technique of storing, in a nonvolatile memory, a part of data required for startup of a computer device in order to reduce startup time of the computer device, as disclosed in Japanese Patent Laid-open Publication No. 7-044325. (hereinafter referred to as Patent Document 1), and Japanese Patent Laid-open Publication No. 2006-309782 (hereinafter referred to as Patent Document 2).
The technique disclosed in Patent Document 1. is aimed at reducing startup time from when a disk storage device is powered on to when it becomes accessible from a computer, and at reducing access time for every reading/writing of data. A nonvolatile memory such as an EPROM is incorporated, in association with an internal processor, in the disk storage device. Stored in the nonvolatile memory are configuration data (addresses in the disk which are required for loading a DOS and the like, the number of cylinders used in the disk, the number of so-called retries on the reading/writing operation, and the like) which are required when loading, into the computer, a basic program OS in the disk. Then, in parallel with an operation to cause the disk to start rotation at the time of starting up the disk storage device, the configuration data are read from the nonvolatile memory into the processor within a time shorter than the disc startup time. As a result, after the startup of disk rotation is completed, the computer can immediately access the basic program in the disk.
Further, in a device disclosed in Patent Document 2, a nonvolatile memory (flash memory) is provided in an HDD. At initial installation of an OS, an OS startup program is stored in the nonvolatile memory. Thereafter, when the system is powered on, ROMBIOS initializes the HDD. Thereby, the startup program stored in the flash memory is read out, transferred to the system body via a system bus, and loaded into a main memory. Conventionally, when the HDD is initialized after the power-on of the system, a spindle motor provided in the HDD is driven. When the spindle motor reaches a steady speed, the startup program is read from the disk and transferred to the system body, and thereby the system is started up. On the other hand, according to the technique disclosed in Patent Document 2, since the startup program, which has conventionally been read from disc, is stored in the flash memory provided in the HDD, it is not necessary to wait until the spindle motor in the HDD reaches the steady speed after the power-on of the system, and thus the startup time of the system is reduced.
Meanwhile, there has been proposed a technique of reducing startup time of a personal computer device by reducing time required for so-called POST (Power On Self Test) process, as disclosed in International Publication WO 02/095556 (hereinafter referred to as Patent Document 3). In the technique disclosed in Patent Document 2, when a user of the personal computer device performs an operation to shut down an OS, a BIOS does not immediately turn off power of the device but restarts the device by software reset, and executes POST. When the POST is completed, the BIOS stores, in a volatile memory, the state of the device just before starting startup of the OS, and causes the device to enter a standby mode as a power-saving mode. At next startup of the device, the BIOS skips execution of the POST and performs only a process for restoring the device from the power-saving mode, thereby immediately starting up the OS. Thus, the startup time of the device can be reduced.
However, the above-described devices have the following drawbacks. First of all, in the devices disclosed in Patent Document 1. and Patent Document 2, the data required for startup are stored in the nonvolatile memory. Use of the nonvolatile memory causes the following problems. First, the reading speed of the nonvolatile memory, such as an NAND flash memory, is generally higher than that of a hard disk but lower than that of a volatile memory. Further, since the nonvolatile memory is a rewritable device, data stored in the nonvolatile memory are low in reliability because a hacker or a cracker can illegally rewrite the data. Further, data destruction might occur depending on the number of rewritings of the nonvolatile memory, which also causes reduction in reliability. Furthermore, in order to secure the reliability, a process for checking the reliability and consistency of data is required when the data are read. As a result, the reading takes more time.
In the technique disclosed in Patent Document 3, the personal computer device is caused to enter the power-saving mode with the result of the POST being stored in the volatile memory, thereby reducing the next startup time. However, for example, when the configuration of the personal computer device is changed during the power-saving mode (for example, when a peripheral device such as a USB memory is mounted), if the device is started as it is, the peripheral device may fail to be normally recognized, leading to malfunction. Although it might be considered to perform the POST process again, the time required for the POST process is not reduced in this case. Further, in the technique disclosed in Patent Document 3, since the personal computer device enters the power-saving mode with holding the result of the POST, time reduction cannot be achieved for processes subsequent to the POST process. To be specific, after the device has entered the power-saving mode with holding the result of the POST, when the device is started up next time, the time required for the POST process is reduced, but a subsequent process for starting up the OS (for example, a process of loading an OS program from an HDD into a main memory, and executing the OS program developed in the main memory) should be performed every time. That is, the time required for the OS startup process cannot be reduced.